⚥ Male or Female? How to Sex a Guinea Pig

Telling a boar from a sow is famously tricky, especially in babies. A gentle, step-by-step way to check.

Sexing guinea pigs is notoriously tricky, and pet shops get it wrong often enough that surprise litters are common. Here is how to check gently and confidently.

How to look

Support the pig against your body or on a towel, belly up, and look at the genital area just above the anus. Press very gently either side.

Male (boar) — a small circle with a raised centre; the penis eases out with the lightest pressure, so the shape reads roughly like an 'i', a dot above a line. Older boars also have obvious testicles either side.
Female (sow) — the opening looks like a 'Y' or small 'V', with no raised centre.

Why it matters

Get it right before you house two pigs together. A misidentified pair is the number one cause of accidental litters, and a pregnant sow is a real health risk. If you are unsure, an exotic vet or experienced rescue can confirm in seconds.

Babies are the hardest to sex and can breed from as young as three weeks, so separate boys and girls early if you are not certain, and always double-check before any two pigs move in together.

Last updated August 2026 · Written from years of keeping long-haired guinea pigs in the Houston area. This is general care information, not veterinary advice. For anything medical, please see an exotic vet.

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